DESCRIPTION (adapted from the application) We will study the etiology of hypertension and nephropathy in the majority of the 1094 African-American patients in the African-American Study of Kidney Disease in Hypertension (AASK). The AASK study is an NIH sponsored clinical multicenter trial comparing the effect of two levels of blood pressure control and three antihypertensive regimens on progression of hypertensive nephropathy in African Americans. There is a disproportionate number of African Americans with hypertensive target organ damage, suggesting a genetic susceptibility in this population; paradoxically, few studies have been performed to evaluate such genetic predisposition to disease in this high risk population. The patients of the AASK study offer a unique opportunity to prospectively determine the genetic factors involved in hypertension and hypertensive target organ damage within a high risk and under-studied population. The proposed studies will immortalize white blood cells from patients to provide a renewable source of tissue and DNA from this unique study group, and follow two approaches in assessing the etiology of hypertension, nephropathy, and their sequelae: 1. Studies are proposed to determine whether polymorphisms in candidate genes for hypertension, renal failure, and cardiac disease, including renin-angiotensin system genes, insulin resistance (beta3-adrenergic receptor and lipoprotein lipase) genes, Liddle's syndrome (beta and gammaENaC) genes, and others are related to hypertension or renal failure, severity/rate of progression of renal disease, severity/refractoriness of hypertension, electrocardiographic left ventricular hypertrophy, cardiovascular morbidity and mortality, and overall morbidity and mortality. 2. Additional studies will employ a new technique, mapping by admixture linkage disequilibrium (MALD), which uses the linkage disequilibrium caused by recent admixture of founder populations to localize genes linked to a particular phenotype within a 5-20 centiMorgan region in a genome-wide screen. By utilizing microsatellite markers from the carefully phenotyped patients of the AASK Study it should be possible to identify regions of interest containing genes associated with hypertension, renal failure, and the outcomes described above for candidate genes.